IVIG Therapy in Pediatric Patients with Suspected Autoimmune Disease

Introduction to IVIG Therapy

The American Academy of Neurology recommends IVIG at 2 g/kg over 5 days for immune checkpoint inhibitor-related Guillain-Barré syndrome and severe neurologic immune-related adverse events, but requires confirmed diagnosis 7

The Mayo Clinic Proceedings suggests that IVIG therapy is not considered standard of care for the diagnosis code D89.9 (unspecified disorder involving the immune mechanism) and lacks established medical necessity without a confirmed autoimmune diagnosis 1, 2, 3
The Annals of the Rheumatic Diseases indicates that IVIG at 0.4-2 g/kg/day for 2-5 days has shown responses in adult-onset Still's disease, but this diagnosis is not established in the patient 2

The Mayo Clinic Proceedings states that standard IVIG dosing protocols typically require 1-2 g/kg body weight, which is significantly higher than the proposed dosing regimen of 90 mg total over 2 days 1, 4, 5, 6
For a 10-year-old patient, assuming average weight of 30-35 kg, standard dosing would be 30-70 grams total (1-2 g/kg), not 90 mg 1, 4

The Journal of Clinical Oncology recommends an autoimmune encephalitis panel, paraneoplastic antibody panel, CSF analysis, MRI brain with and without contrast, and EEG to evaluate for encephalitis, demyelination, or other structural abnormalities 7
IgA deficiency screening is mandatory before IVIG administration to prevent anaphylactic reactions from anti-IgA antibodies 1, 4, 5, 6

The Mayo Clinic Proceedings notes that underdosing IVIG provides no benefit while exposing the patient to risks and costs, and inadequate monitoring increases safety risks 1, 4, 5, 6
The Annals of the Rheumatic Diseases suggests that IVIG at 1-2 g/kg divided over 1-2 days monthly for 1-6 months is established for dermatomyositis/polymyositis, but this patient lacks myositis features 2